Electronic devices such as electronic flat panel displays and semiconductor integrated circuits generally are manufactured by performing a sequence of process steps in various process chambers. Such process steps commonly include steps performed within plasma process chambers, such as a deposition step performed in a plasma-enhanced chemical vapor deposition chamber or a plasma sputtering chamber, or an etch step performed in a plasma etch chamber. Any chamber for performing a step in the manufacture of an electronic device while a plasma exists within the chamber is considered a plasma process chamber.
Malfunctions sometimes occur while a workpiece is undergoing processing within a plasma process chamber. Such malfunctions can include a damaged chamber component, a chamber component that requires cleaning or other routine maintenance, or a damaged workpiece. If a plasma process is not halted after a malfunction occurs, there is a risk of producing more serious damage to the chamber components or the workpiece. Therefore, it is important to detect such malfunctions as quickly as possible so that the plasma process can be halted.